ABS resins show excellent balance between impact resistance and workability and have been widely used in various fields, e.g., interior and exterior components for vehicles such as automobiles, housings of various home electric appliances and OA equipment, and fields of other miscellaneous goods. The ABS resins are applied not only to injection molding but also to extrusion molding, such as sheet extrusion. The ABS resins, however, have a disadvantage, poor weather resistance, because the butadiene rubber polymer contained as the rubber component can be readily decomposed by, for example, ultraviolet rays. In order to solve such a disadvantage, ASA resins containing an acrylic rubber, which have improved weather resistance, have been used in practice. The ASA resins have excellent weather resistance, but have disadvantages, i.e., low impact resistance, color developing properties, elongation, and tensile strength.
Patent Literature 1 discloses a thermoplastic resin composition that comprises a composite rubber composed of a diene rubber having a specific molecular weight and an acrylic ester polymer and that has improved impact resistance, weather resistance, and molding workability. Unfortunately, the thermoplastic resin composition has disadvantages, i.e., insufficient color developing properties, gloss, and residence heat stability.
Patent Literature 2 discloses a thermoplastic resin composition that comprises a maleimide copolymer and a graft copolymer comprising a composite rubber composed of a conjugated diene rubber polymer and an acrylic ester rubber polymer and that has improved heat resistance, weather resistance, molding workability, and also surface appearance of a molded article. Unfortunately, the thermoplastic resin composition has disadvantages, i.e., insufficient color developing properties, gloss, and residence heat stability.
A composition composed of a polycarbonate resin and an ABS resin (hereinafter may be referred to as PC/ABS resin) has excellent impact resistance, heat resistance, and molding workability and therefore has various uses such as vehicle parts, household appliances, and business machine parts. Since the ABS resin, which contains butadiene rubber segments, is inferior in weather resistance, an AES resin containing an ethylene-propylene-unconjugated diene rubber in place of the diene in the main chain and a composition composed of an ASA resin containing an acrylic rubber and a polycarbonate resin (hereinafter may be referred to as PC/ASA resin) have also been disclosed. For example, Patent Literature 3 discloses a thermoplastic resin composition comprising an ASA resin containing an acrylic rubber having a specific structure and a polycarbonate resin.
Patent Literature 4 discloses a thermoplastic resin composition that comprises an ASA resin containing a siloxane rubber having a specific structure and an acrylic rubber, a polycarbonate resin, and a hard copolymer and that has improved molding workability, weather resistance, and molding appearance and also has improved low temperature impact resistance. Unfortunately, the thermoplastic resin composition has insufficient improvements in the balance between impact resistance (in particular, low temperature impact resistance) and molding workability (fluidity), the defects on appearance such as a pearl-like surface of the molded article, and gloss unevenness. Deterioration of residence heat stability is not mentioned at all.
A resin composition composed of a polyamide resin and an ABS resin (hereinafter may be referred to as PA/ABS resin) has excellent impact resistance, heat resistance, and molding workability and thus has various uses such as interior and exterior components for vehicles, household appliances, and business machine parts. Since the ABS resin, which comprises a butadiene rubber, is inferior in weather resistance, the composition has a disadvantage of significant weathering discoloration. For example, Patent Literature 5 discloses a thermoplastic resin composition composed of a polyamide resin and an imidized ABS resin for an automobile wheel cover. In spite of a composition for an automobile wheel cover, no description is found on any test under rainy conditions and its chemical resistance.
Patent Literature 6 discloses a resin composition composed of an ASA resin including an acrylic rubber not containing a diene polymer in the main chain and a polyamide resin (hereinafter may be referred to as PA/ASA resin). Unfortunately, the molding workability (fluidity) and the balance between impact resistance (in particular, low temperature impact resistance) and weather resistance are still insufficient, and its chemical resistance is not described at all.
Furthermore, the ABS resin is inflammable, and a demand for flame retardation is increasing in light of safety. Accordingly, various flame-retarding technologies have been disclosed. Patent Literature 7 discloses a flame-retardant thermoplastic resin composition that comprises a rubber-reinforced styrene resin, an organic phosphorus compound, and a composite rubber graft copolymer and that has improved flame retardance, impact resistance, light resistance, and molding workability. Unfortunately, the composition has insufficient color developing properties.
In sheet molding or film molding by extrusion molding, as the thickness of the film is reduced, the product is required to have high tear resistance and high strength, i.e., the extruded article is required to have high elongation and high tensile strength. Patent Literature 8 discloses a composite rubber composition for sheet extrusion having excellent weather resistance and appearance. Unfortunately, the composition has insufficient elongation and tensile strength.